Timing chain replacement

[Shikaroka]

Are there any downsides to replacing the chains?
(I know that sounds crazy)

Since I have about 250k miles on my Burb....
I know the IP is original and I'd say there is a good chance that the chains and cogs are original too.

If I replace the chains, is there a chance that I will wear out an IP (any faster) or cause it to show it's age?
I hate to open up a money pit, if you know what I mean.

I know I need to change them, I just want to be prepared.
Does any of this make sense?

[Patrick m.]

What else is original? (incredible life for an I.P. by the way)
May want to consider the following parts as well:
Balancer, crank pulley, and water pump (of course the related gaskets)

This round of service should not affect IP life, however, at 250K you're on borrowed time anyway.

The down side would be about $1200.00 if you do it yourself (IP being 800 of that)

[JDave]

I replaced my chain with the gears at about 180K and they showed no wear. I had to take off my front cover and I figured while I was in there I should do it, but I was surprised how good the chain looked.

[Robyn]

Barring unusual conditions most of the wear will be in the chain and not the sprockets.
I replaced the chain only at 230K on the 94 and it was back up tight as a fiddle string and works fine.
Unless the teeth on the sprockets show wear a new chain will suffice.

Saves a lot of cost too as the chain is cheap.

Robyn

[sailun]

I've been thinking about doing a new chain, in my quest for MPG, and another 160k miles.

Will this produce noticable differences in restoring the timing, power, and mpg ?

I really want to know I'm gonna see some payback, before tackling another big job.

Also what do I need for special tools to rotate the engine, and measure the slack ? What's a good go/nogo measurement for chain slack ?

[GSE2SCHMIDT]

Isn't there some way to check the chain without pulling everything apart?

I know on gasoline engines sometimes we would check slack in the chain by popping the distributor cap and hand turning the engine both ways (plugs out helps) and seeing how many degrees slop for the distributor rotor to turn. I think something like Plus/minus 5 degrees (10 total) was good but it may be higher.

I know there is no distributor but I currently have my oil filler neck off my engine and I can clearly see the top timing gear for the pump. Hand turning may be accomplished a tool and patience.

Of course if your changing out glow plugs it would go better. Don't think it would be worth changing glow plugs and risk dropping one off if you don't have glow plug issues.

Anybody out there try something like this? Someone out there may have an engine and try it with the cover off and let us know

[DickWells]

I wish I had my 6.5 R&R Guide with me. There's an article in there on this whole thing.
Anyway, with the oil filler neck off, you can easily check chain slack. Just watch the amount of rotation on the balancer (timing marks) as you rotate the crank back and forth, while noticing when the IP moves. There are limits in the book, but I can't remember what they are from this distance. Thing is, your injecter timing will go retarded as the chain wears. So. if there's a lot of noticeable slack, then, it seems to me that you've answered the question. Probably a good idea to get in there and replace at least the chain.
You can do a short term band aid fix by advancing the IP a little to compensate for the retardation, but it's not the best solution.
Also, if you have some extra money, and you plan on keeping this rig for a long time, you could put in Phazer Gears. One of the best things I ever did to the old Sub. But, not cheap! Don't know what your plans are for the long-haul, what with that kind of mileage. Congrats on that, by the way. You're a lucky man!
Good luck.
Dick W.

[Shikaroka]

however, at 250K you're on borrowed time anyway.

Yeh, that's what I've been thinking.

I may just wait until I need/want to replace the IP, and do it all at once.
I want to upgrade the water pump and thermostat housing while I'm at it, but the total keeps growing and I don't know if I can afford to do it all at once.

I'm pretty mechanical (used to work in a machine shop and several garages, and do all of my own work), how long do you think it would take me to do the chains if that's all I do?

[john8662]

Robyn has a point here that I do now believe is valid...

Just replace the chain and not the whole set?

In most cases the chain can be serviced and it'll be plenty tight and in spec for sure.

A new chain is REALLY tight and is difficult to move either way once installed.

But, I'd still recommend replacing the whole set if you've got an engine with 200+k miles on it at any rate.

The unfortunate thing about these parts now days is that the gears on the engine now are likely superior to that of the new aftermarket unit you're buying at the parts store.

J